<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!-- jQuery文件。务必在bootstrap.min.js 之前引入 -->
    <script src="//cdn.bootcss.com/jquery/1.11.3/jquery.min.js"></script>
    <style>
        #iu{
            background: #123;
        }
    </style>
</head>
<body>

<script>
    $("body").html('<div id="iu">123132</div>')
</script>
</body>
</html>